Several factors were involved during the manoeuvring for the dummy run: low relative airspeed, steep left turns, and forward C of G position, which would have increased the stall speed and decreased the margin between airspeed and stall. The aircraft likely stalled in a climbing attitude. This would result in a sharp roll to the right. With the aircraft's low altitude, recovery before ground impact would be difficult. Tree-strike evidence indicates that at impact the aircraft was in a 42 nose-down attitude in a right bank of about 105. On ground contact, the aircraft cartwheeled and tumbled. Examination of the aircraft wreckage revealed no defects that could have led to the accident. Damage to the two propellers indicated that both engines were producing power at impact.Analysis Several factors were involved during the manoeuvring for the dummy run: low relative airspeed, steep left turns, and forward C of G position, which would have increased the stall speed and decreased the margin between airspeed and stall. The aircraft likely stalled in a climbing attitude. This would result in a sharp roll to the right. With the aircraft's low altitude, recovery before ground impact would be difficult. Tree-strike evidence indicates that at impact the aircraft was in a 42 nose-down attitude in a right bank of about 105. On ground contact, the aircraft cartwheeled and tumbled. Examination of the aircraft wreckage revealed no defects that could have led to the accident. Damage to the two propellers indicated that both engines were producing power at impact. The aircraft likely entered a stall during a low-level turning manoeuvre from which recovery was not possible.Findings as to Causes and Contributing Factors The aircraft likely entered a stall during a low-level turning manoeuvre from which recovery was not possible.